Immunological Memory & Vaccinations - Exam 4

What is the main purpose of the immune system?

To recognize and eliminate pathogens while distinguishing self from non-self

What are the two main branches of the immune system?

Innate (nonspecific, rapid) and Adaptive (specific, slower, has memory)

What is innate immunity?

The first line of defense, includes barriers, inflammation, and phagocytosis

What is adaptive immunity?

Immune response specific to a particular antigen; develops memory cells

What is immunological memory?

The immune system's ability to respond more rapidly upon re-exposure to an antigen

What is an antigen?

Any molecule that triggers an immune response and binds to antibodies or T-cell receptors

What is an antibody?

A protein produced by B cells that binds specific antigens (diagram pg 12: Y-shaped molecule).

What part of the antibody binds the antigen?

The variable region (Fab fragment)

What part of the antibody determines its class?

The constant region (Fc fragment)

What are the five major classes of antibodies?

IgG, IgA, IgM, IgE, IgD

What are cytokines?

Chemical messengers that regulate immune cell communication and activation

What is the function of MHC molecules?

Present antigens on cell surfaces for T-cell recognition

Difference between MHC I and MHC II?

MHC I = all nucleated cells (presents to CD8+); MHC II = APCs (presents to CD4+)

What is the function of B cells?

Produce antibodies and develop into memory or plasma cells

What is the function of T helper cells (CD4+)?

Activate B cells, macrophages, and cytotoxic T cells

What is the function of cytotoxic T cells (CD8+)?

Destroy virus-infected or abnormal cells

What triggers adaptive immunity?

Antigen presentation to T and B cells

What is the difference between primary and secondary immune responses?

Primary = first exposure, slower; Secondary = faster, stronger, due to memory cells

What is active immunity?

Immunity developed after exposure or vaccination; produces memory

What is passive immunity?

Temporary immunity through transfer of antibodies (e.g., maternal IgG)

What are the four types of acquired immunity?

Natural active, natural passive, artificial active, artificial passive

What is a vaccine?

A preparation that induces protective immunity by exposing the immune system to an antigen

How do vaccines work?

Stimulate B and T cells to form memory without causing disease

What are live attenuated vaccines?

Contain weakened pathogens that replicate slightly (e.g., MMR)

What are inactivated vaccines?

Contain killed pathogens that can't replicate (e.g., flu shot)

What are subunit vaccines?

Contain only antigenic parts of the pathogen (e.g., Hepatitis B)

What are mRNA vaccines?

Use genetic instructions to make a viral protein that triggers immunity (e.g., COVID mRNA)

What are conjugate vaccines?

Combine weak antigens with strong carrier proteins to boost response

What is a toxoid vaccine?

Uses inactivated toxins (e.g., tetanus, diphtheria)

What is herd immunity?

Protection of the population when a large portion is immune, reducing spread

Why are booster shots needed?

To re-stimulate memory cells and maintain antibody levels

What are adjuvants?

Additives that enhance the body's immune response to an antigen

What is a side effect of vaccination?

Usually mild inflammation or fever as the immune system activates

What is the function of the p24 antigen in HIV testing?

It's an early marker of HIV infection before antibodies appear

How often does the CDC recommend HIV testing?

At least once per year for most adults

What does ART stand for in HIV treatment?

Antiretroviral therapy - a combination of drugs that block different replication stages

What is the function of reverse transcriptase inhibitors?

Prevent HIV from converting RNA into DNA

What is the function of integrase inhibitors?

Block HIV DNA from entering host cell DNA

What is the function of protease inhibitors?

Prevent formation of new infectious virus particles

What is the goal of modern HIV therapy?

Keep viral load undetectable, prevent AIDS, and allow normal lifespan